Our kitfox, series 7, W/912ULS, is set up with two separate electrical systems with a cross tie. (Two alternators, two busses, two batteries). The primary system feeds the radios, the aux system feeds the high draw stuff - we have the standard strobes/position lights and halogen landing/taxi lights so it pulls amps.

Since the system permits running anything electrical, including the starter, on either or both systems, I decided to use the traditional Odyssey PC680 for the primary side because of its recognized reliability; and, try a low cost equivalent gel cell for the aux system - since, if it pooped - it would not be an operational problem anyway.

The Odyssey PC680 on the primary side has worked out perfectly (currently it is 2 years old).

The bargain battery I installed on the aux system, a bit over a year old now, sold under the brand "Werker" model WKA12-18NB at "Batteries minus", gradually lost its ability to take and hold a charge at all. FYI - the system was constantly checked and monitored to know that the remainder of the system, other than the battery, was operating correctly.

As it worked out - I installed a new Odyssey PC680 after removing the brand X unit for the aux system. The brand X unit was pretty much a waste of time and money,

The brand X unit, of course, was handcrafted in the far east by skilled artisans in china. I think it is also a fair statement that the little "ISO 9001" logo on the side of the battery is a step beyond meaningless - it is misleading, but, then, I may be unfairly judging the significance of the "ISO 9001" notation - it may only apply to the box the battery came in - not the guts of the battery itself. (don't get me going on quality systems that companies brag about but don't apply in practice - I deal with that in my day job all the time).

Anyway - if there is a contest between these two batteries, it is no contest - the Odyssey wins - costs a bit more, but then, sometimes the other guys who sell for less might know know what their stuff is worth.....

Good info Dave, thanks. That's consistent with my experience with batteries also. I'm installing an Odyssey PC680 in my Super Sport also, though only one. I don't know how much lighter it is than the Kitfox supplied battery but it looks to be a coule of pounds. I'm then using a battery box/bracket sized for the PC680 from Van's rather than the Kitfox supplied plastic box which is considerably larger.

I also did not care for the plastic battery box & fabricated an aluminum box that exactly fit the Odyssey battery. The attached photo shows what the aluminum box looks like & where it fits - also the aux alternator location. FYI - the second battery is behind the pilots seat, accessible through a hinged door on the back of the seat pan - that also has a fabricated aluminum box; and, now a new PC680.

Fortunately, we are not cats.....curiosity is a good thing for our species. My decision to go with a dual electrical system had its genesis when I was pondering the practical continuous output from the integral Rotax alternator in the context of what I wanted to have on the plane to start with (day-night VFR); and, what I might add to the electrical demand later. Then other considerations started seeping into the decision; such as, a) just about every system failure I have had on an airplane has had to do with the electrical system, b) the 912ULS, I am told, isn't very easy to flip-start, c) we plan on a lot of extended cross country and back country airports (where electrons are harder to come by than in a metro 'port if you really need them). d) a little extra battery capacity is a good thing in Minnesnowta and Buuurmidji. On the other hand, considered the extra weight and $; but, I already jeopardized my children's inheritance during the build; and, I am kinda on the back side of the bell shaped curve for body weight anyway so I put the pounds in the airplane rather than changing my eating habits.

I have a PC680, which holds a charge forever, but with the long battery
runs makes hard starting with the IO-240 in the winter. I sometimes
resort to a second battery on the passenger side floor hooked in with
jumper cables for really cold weather starting (I remove it before flight)

Next year I'll upgrade to a mobile ground support power unit, just like
we had in the Navy ...

Jeff.

Quote:

Originally Posted by RandyL

Good info Dave, thanks. That's consistent with my experience with batteries also. I'm installing an Odyssey PC680 in my Super Sport also, though only one. I don't know how much lighter it is than the Kitfox supplied battery but it looks to be a coule of pounds. I'm then using a battery box/bracket sized for the PC680 from Van's rather than the Kitfox supplied plastic box which is considerably larger.

I noticed my engine cranking becoming a bit more sluggish when I moved the PC680 in my RV-3 back behind the seat. I'm using 4 ga welding cable, how about you? I was wondering if going to 2 ga would help it.

If I may join in here. I also use the Odyseey battery and found it to be very good. The cold cranking amps do the job for me. I have it mounted behind the seat. I used a aluminum battery box and attached it to the cross member behind the seat using adel clamps. I used #6 copper then went to the #4 welding lead. Good move and it starts much better.

I have been interested in your discussion as I brought this up on the Matronics list. I got the hell kicked out of me for using such a huge battery. Try starting your plane when its 0 and you find out why. I guess we all don't live in Florida ha.